1. Field of the Invention
The present invention relates to a rechargeable battery. More particularly, the present invention relates to a rechargeable battery having an improved fixing structure for an electrode assembly of the rechargeable battery.
2. Description of the Related Art
Unlike a primary battery that is incapable of being recharged, a rechargeable battery is a battery that can be repeatedly charged and discharged. A low-capacity rechargeable battery having a single cell is used in small portable electronic apparatuses, such as mobile phones, laptop computers, and camcorders. A large-capacity rechargeable battery that includes a plurality of rechargeable cells connected in a pack shape is used as a power source for driving a motor of a hybrid electric vehicle and the like.
Rechargeable batteries are manufactured in various shapes, for example a cylindrical shape and a square shape.
Rechargeable batteries are connected in series so as to be used for driving a motor of an electric vehicle, which requires large power, thereby forming a large-capacity rechargeable battery module.
A rechargeable battery is typically constructed with an electrode assembly in which a cathode and an anode are disposed with a separator interposed between the cathode and the anode, a case accommodating the electrode assembly, and a cap assembly that closes and seals one base end of the case.
When the rechargeable battery has a cylindrical shape, regions where an active material is not coated are formed on the cathode and the anode of the electrode assembly. The uncoated cathode region and the uncoated anode region are disposed to be in opposite directions from each other.
An anode current collecting plate is attached to the uncoated anode region, and a cathode current collecting plate is attached to the uncoated cathode region. The anode current collecting plate is electrically connected to the case, and the cathode current collecting plate is electrically connected to the cap assembly, thereby leading a current to the outside. Accordingly, the case serves as an anode terminal, and a cap plate provided in the cap assembly serves as a cathode terminal.
The cathode current collecting plate and the cap assembly are electrically connected to each other by a lead member made from an electrically conductive metal. The cap assembly are welded to the lead member and then inserted into the case. After the cap assembly is inserted into the case, the cap assembly is clamped and fixed to the case.
In such a manner, the electrode assembly is electrically connected to the cathode current collecting plate and the anode current collecting plate. In order to maintain stable connection of the electrode assembly and the current collecting plates, the electrode assembly needs to be stably fixed within the case.
Since a space into which an electrolyte is accommodated is formed between the electrode assembly and the internal surface of the case, when an external impact is applied against the case, the electrode assembly may undesirably move within the case. In particular, when the rechargeable battery is applied to a moving apparatus such as a vehicle, or a vacuum cleaner, constant impacts are applied due to the use of the movable apparatus against the external environment, and thus the electrode assembly may freely move within the case.
When the electrode assembly freely moves within the case, defective contacts may occur in a contact portion of the electrode assembly and the current collecting plate. If a defective contact occurs between the electrode assembly and the current collecting plate, electrical resistance in the contact portion may increase, and the output of the rechargeable battery may deteriorate. Further, if the electrode assembly moves too much, the contact portion, may become separated, and thus charging and discharging may not be able to be performed.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.